The present invention relates to a vehicle transmission with an automatic clutch, and more particularly to means for controlling reengagement of a clutch.
A vehicle transmission with an automatic clutch is known in which for gear shifting a clutch is disengaged with the assistance of a vacuum of a source of vacuum, via a control valve having a solenoid actuated clutch release valve and a clutch servo. The solenoid actuated clutch release valve connects the clutch servo to the source of vacuum when a solenoid therefor is energized to disengage the clutch. The reengagement of the clutch commences as soon as the flow of current to the solenoid for the clutch release valve is cut. The solenoid then allows the clutch release valve to disconnect the clutch servo from the source of vacuum. The vacuum in the clutch servo is reduced at a speed determined by effective flow sectional area of an air bleed conduit means which is opened when the clutch release valve disconnects the clutch servo from the source of vacuum.
When designing this known vehicle transmission, the effective flow sectional area of the air bleed conduit means must be determined appropriately considering that, for the first, if the effective flow sectional area is excessively great, the clutch engages roughly and, for the second, if the effective flow area is excessively small, the clutch slips excessively.
This known vehicle transmission has a shortcoming that since the effective flow sectional area of the air bleed conduit means determines a take-up characteristic of the vacuum reduction, the take-up characteristic is not variable in connection with operating conditions of the engine and is not adjustable in connection with the condition of the clutch.